Division of Neuropathology, Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine,Philadelphia, Pennsylvania 19104, USA.
RNA. 2010 Jan;16(1):70-8. doi: 10.1261/rna.1869710. Epub 2009 Nov 19.
Piwi proteins such as Drosophila Aubergine (Aub) and mouse Miwi are essential for germline development and for primordial germ cell (PGC) specification. They bind piRNAs and contain symmetrically dimethylated arginines (sDMAs), catalyzed by dPRMT5. PGC specification in Drosophila requires maternal inheritance of cytoplasmic factors, including Aub, dPRMT5, and Tudor (Tud), that are concentrated in the germ plasm at the posterior end of the oocyte. Here we show that Miwi binds to Tdrd6 and Aub binds to Tudor, in an sDMA-dependent manner, demonstrating that binding of sDMA-modified Piwi proteins with Tudor-domain proteins is an evolutionarily conserved interaction in germ cells. We report that in Drosophila tud(1) mutants, the piRNA pathway is intact and most transposons are not de-repressed. However, the localization of Aub in the germ plasm is severely reduced. These findings indicate that germ plasm assembly requires sDMA modification of Aub by dPRMT5, which, in turn, is required for binding to Tudor. Our study also suggests that the function of the piRNA pathway in PGC specification may be independent of its role in transposon control.
Piwi 蛋白，如果蝇 Aubergine（Aub）和小鼠 Miwi，对于生殖细胞的发育和原始生殖细胞（PGC）的特化是必不可少的。它们结合 piRNA，并含有对称二甲基精氨酸（sDMA），由 dPRMT5 催化。果蝇中 PGC 的特化需要母体细胞质因子的遗传，包括 Aub、dPRMT5 和 Tudor（Tud），这些因子集中在卵母细胞后端的生殖质中。在这里，我们表明 Miwi 以 sDMA 依赖性的方式与 Tdrd6 结合，Aub 与 Tudor 结合，证明 sDMA 修饰的 Piwi 蛋白与 Tudor 结构域蛋白的结合是生殖细胞中保守的相互作用。我们报告说，在果蝇 tud(1)突变体中，piRNA 途径是完整的，大多数转座子没有去抑制。然而，Aub 在生殖质中的定位严重减少。这些发现表明生殖质的组装需要 dPRMT5 对 Aub 的 sDMA 修饰，这反过来又需要与 Tudor 结合。我们的研究还表明，piRNA 途径在 PGC 特化中的作用可能与其在转座子控制中的作用无关。
